Interview: Carswell spoke to IBTimes UK about leaving Ukip, his new book and his theory of populism.

Western democracies could face a series of strongmen leaders as "hideous" and "incompetent" anti-oligarch radicals, such as Marine Le Pen, inadvertently legitimise them, Douglas Carswell said on 9 March. The Clacton MP, who quit Ukip in March, expounds on the theory in his new book, Radical: How to Overthrow the Emerging Oligarchy.

"I look as far back as Ancient Greece, Ancient Rome and the republics of Venice and the republics of the Netherlands and I look at what makes a successful society, why do some countries flourish?" Carswell told IBTimes UK.

"I identify several ingredients: independence, being free from internal parasites with dispersed power and also being interdependent – being able to specialise and exchange and trade with your neighbours."

He added: "We're starting to actually see a powerful elite in the heart of the West that's making public policy for its own benefit, it's rigging the system with monetary policy so that it increases the wealth of those with assets and we're also seeing a political oligarchy emerging.

"In response to this you get these new radical movements today as we have had in the republic of Rome, Venice and the Netherlands, but the anti-oligarch radicals are so incompetent or hideous they actually justify the existence of a strongman, that is where we are today."

Carswell, 45, derides members of the political class as "Davos men" – a reference to the annual World Economic Forum in Switzerland – and attacks "party bosses", who undermine rebellious MPs and guard safe seats. He wants to scrap the First Past the Post voting system and introduce recall, a process that enables constituents to table a motion of no confidence against their own MP.

But Carswell's own radicalism has been questioned after he quit Ukip. When he defected from the Conservatives to the Eurosceptic party in 2014, Carswell called a by-election. There was no such move this time around.

The Brexit Club: The Inside Story of the Leave Campaign's Shock Victory author Owen Bennett, who unearthed Carswell's plot to "neutralise" Nigel Farage in the EU referendum, has branded the free marketeer as "hypocritical" and "self-serving" over the decision not to call a by-election. Carswell, however, argued that he was being "tediously consistent".

"When I left the Conservatives and joined Ukip I was crossing the floor [of the House of Commons]," he told IBTimes UK.

"If you had a by-election every time an MP lost or resigned the whip, that would actually strengthen the power of party bosses. It would be something that they could threaten rebellious MPs with."